Differential radiocontrol



Nov. 30 1926. l I H. W. WEBBE DIFFERENTIAL RADIOCONTROL Filed June 18, 1925 IIMIII .F

i La): gmmm n OCAN Patented Nov.l 30, 1926.

HAROLD W. WEBBE, OF COLUMBUS, OHIO.

DIFFERENTIAL RADIOCONTROL.

Application filed June 1S,

rlhis invention relates to a system for controlling objects at a distance by radio in which system tuning forks as a means of differential control are adapted to the use of audion lamps. The use of tuning forks with coherers in radio is not new but appears to have been abandoned at the time of the adoption of crystal detectors and the audion lamp, due no doubt to the small currents used by these devices. However, a method of remote control which is very select-ive and quite free from interference is possible, provided that currents of sufficient amperage can be obtained to actuate these forks electrically.

It is therefore proposed to* use a telephonic or microphonic relay in connection with a radio power amplifier. By actual tests, low resistance relays of this type have been found to be very positive and accurate in their action and because of their aperiodic nature, their frequency can be instantly changed so as to select different tuning forks as desired. I am aware that it is old to use a vibrating diaphragm to actuate a vibrating member and to give it a periodic quality in resonance with that member. This would limit its use to a vibrating body. It is the object of this invention to leave the receiver diaphragm unlimited or aperiodic so as to use the device differentially to select at will any number of vibrating bodies.

Another object of this invention is to provide means for overcoming the inertia of tuning forks as an objectionable feature. The inertia of a tuning fork, when set in motion, causes the fork to continue to vibrate an appreciable time after the actuating force is removed. Then instantaneous control is desired this is distinctly disadvantageous.. Cuntz in his Patent 927,641 for signaling iminerses the forks in liquid, or using magnetic forks places copper plates in close proximity to dampen their movement and render them more responsive. This method appears crude and tends to interfere with the freedom of the fork. I propose to overcome this tendency by using forks in pairs so that one fork will close and lock a relay while the second fork restores the rst to normal. To the first relay is connected the device to be controlled. Any number of pairs may be used provided that harmonic notes are avoided, hence a large number of devices may be controlled differentially.

1923. Serial No. 646,044.

In the drawings the figure is a diagrammatical representation o f a radio system with a transmitter, receiver, amplifier, and the tuning forks in circuit. v

Referring more particularly to the drawings, a tuning fork A at a radio transmitting set modulates a radio carrier wave and is received at a. radio receiving set as a series of impulses at the audio frequency of A. These impulses are amplified and actuate the telephonic relay T Tuning fork A1 is in circuit with a battery and telephonic relay T Tuning fork A1, having the same period of vibration as fork A, goes into motion and closes the relay R1 which locks and lights the lamps L Tuning forks B and B1 restore this circuit to normal.

Telephonie relay T is merely a commercial telephonic receiver with a special contact such as a wire with platinum sleeve stretched across the diaphragm so as to engage a raised platinum ridge in the center of the diaphragm when it is in motion.

The advantages of this method for remote control over those in use today are that it permits the use 0f one radio carrier, eliminates the use of ratchet devices for selectivity, and also eliminates the use of .expensive and sensitive galvanometers and other relays iny the plate circuit of audion lamps. The apparatus in the plate circuit of lan audion lamp is affected alike by interferences as well as signal, whereas in this system the inertia of the forks resist spasmodic interference. It will thus be seen that my method is extremely economical and accurate. y

Having thus described my invention, I claim:

In a system for the control of an object at a distance by radio, a radio transmitter including a pair of tuning forks of different periods of vibration for modulating the radio waves and means for selectively permitting either of said forks to govern the group frequency, a radioreceiver, a power amplifier connected thereto, an aperiodic relay operated by said power amplifier for making or breaking an electric contact, said relay being adapted to allow the impulse in the circuit oscillating said forks to instantly readjust itself to any change in the incoming audio frequency impulses, a source of power and a pair of forks governing coils SNI connected to said Contact, a plurality of forks of different yperiods corresponding 13o-'the periods of V"the forks'in the-transmitting circuit, and adapted to be set into vibration-by the fork governing coils, anelectrio--irouit adapted to be closed when one of said last mentioned forks is Vibimitedfand.lanVA second ylorated.

In testimony whereof I affix my signature.

HAROLD V. WEBER 

